2.3.0b1

This marks the feature freeze of the 2.3 branch. Below is a short overview of what has changes with respect to 2.2:

• Semi-bugs/features:
  • scale_by_problem_size for path goals now only uses number of active time steps.
  • Much improved scaling of initial derivatives.
  • Improve branch allocation of ControlTreeMixin.
  • Fix inconsistencies in internal API w.r.t. what methods can return symbolic values.
• Improved checks:
  • Sanity checks on goals, e.g. function ranges. Some models may fail the checks now, but if they do the goal in question did not make much sense anyway.
• New features:
  • Vector goals (mostly a performance improvement)
  • Optional more generic/optimal way of translating goals from current priority to the next. See keep_soft_constraints option added in commit f6eb00d.
  • Can now provide a custom (initial) seed to SimulationProblem.
  • Allow extra variables to appear in path expressions
• New examples, in particular showing the use (and strength) of using HomotopyMixin for channel flow.
• Many, many small optimizations and refactorings for performance reasons. Especially useful for large models with many variables.